JP2024513390A - Materials and configurations for protection of purpose materials - Google Patents

Abstract

Passivation regions and device configurations are described herein. The passivation regions can be configured to seal against diffusion of target materials from an underlying region into the passivation region and/or through the passivation region. The passivation regions can also be configured to seal against diffusion of external supplies or ambient materials into the passivation region towards the underlying region and/or through the passivation region.

Description

(Cross reference to related applications)
This application is a United States patent application filed on April 2, 2021, the contents of which are incorporated herein by reference in their entirety for all purposes. Claims priority of application no. 63/170,108.

(Technical field)
The subject matter described herein generally relates to the protection or passivation of target materials, such as the passivation of lithium layers within neutron generating devices.

There are many applications where it is desirable to protect or passivate materials within a device. One such application is boron neutron capture therapy (BNCT), which represents a relatively new modality for the treatment of various types of cancer, including the most difficult types. BNCT is a technique that aims to selectively treat tumor cells while sparing normal cells using boron compounds. A substance containing boron is injected into the blood vessels, and the boron collects within the tumor cells. The patient then receives radiation in the form of a neutron beam. Neutrons are produced by the interaction of a proton beam with a neutron-generating material, such as lithium or beryllium, positioned on a target substrate. The resulting neutron beam is slowed and focused on the patient, where the neutrons react with boron and selectively kill tumor cells.

The neutron-generating material can be positioned as a layer, coating, or coating that can interact with certain types of particles or plasma. Lithium is a conventional example, but it is highly reactive and corrosive which is difficult to handle in normal ambient conditions (such as air at room temperature such as those found in a typical laboratory space). metal. Lithium reacts violently with moisture, nitrogen, and/or oxygen in atmospheric air and rapidly discolors and/or oxidizes. Lithium can be found in nitrides and hydroxides (e.g., lithium hydroxide (LiOH and LiOH-H ₂ O), lithium nitride (Li ₃ N), and lithium carbonate (the result of secondary reactions between LiOH and CO ₂ Li ₂ CO ₃ )), which can be exfoliated from the substrate in the form of dust. Air and moisture act as catalysts for such reactions.

For safe handling, in one example, the lithium can be attached to a substrate inside a glove box and filled with an inert pure gas (eg, argon). Transfer of lithium from the glove box to the work area requires the use of a "drying chamber" where the amount of moisture in the air is low enough to prevent the lithium from oxidizing or discoloring too significantly. However, humans working in drying chambers naturally introduce moisture, eliminating the benefits provided by drying chambers. Furthermore, the construction of drying rooms is complex and expensive.

Attempts to address the above drawbacks have met with limited or no success, depending on the particular application in which lithium is used. The synthesis of Li ₃ N on the surface of lithium targets has been proposed. Disadvantages of such an approach include the inability to control the thickness of the Li ₃ N layer and the high diffusion coefficient of lithium in Li ₃ N. Moreover, such approaches do not eliminate the risk of contamination or oxidation, even in ultra-high vacuum (UHV) conditions.

A thick layer of lithium covered or protected by a thin layer of stainless steel (SS) has also been proposed as a solution. Such approaches suffer from limited time intervals (eg, only 10 minutes) in which lithium is protected and viable. Additionally, approaches associated with thick coatings applied on top of the accelerator target material result in slowing down of the accelerator particles and thus lower yields or complete hindrance of the desired reaction.

Oxidation-resistant layers of beryllium (Be) and/or aluminum (Al) have also been proposed. Disadvantages associated with such an approach include the high reactivity between lithium and aluminum when they come into contact and the rapid diffusion of aluminum through the lithium. Additionally, beryllium is dangerous and difficult to handle.

For these and other reasons, a need exists for improved systems, devices, and methods that promote passivation of materials.

Exemplary embodiments of systems, devices, and methods for protection or passivation of materials of interest are described herein. The passivation region can be configured to seal against diffusion of target material from the underlying region into (and/or through) the passivation region. The passivated region can also be configured to seal against diffusion of external supplies or ambient substances into (and/or through) the passivated region toward the underlying region. Passivated regions with single and multilayer configurations are described. Exemplary embodiments are described in the context of neutron generation applications where the target material is lithium.

Other systems, devices, methods, features, and advantages of the subject matter described herein will be or will become apparent to those skilled in the art upon consideration of the following figures and detailed description. It is intended that all such additional systems, methods, features and advantages be included within this description, be within the scope of the subject matter described herein, and be protected by the accompanying claims. ing. No features of the exemplary embodiments should be construed as limitations on the appended claims in any way unless such features are explicitly recited in the claims.

Details of the subject matter described herein, both with respect to structure and operation thereof, may be apparent from consideration of the accompanying figures, in which like reference numbers refer to like parts. The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the subject matter. Additionally, all illustrations are intended to convey concepts, and relative sizes, shapes, and other detailed attributes may be illustrated diagrammatically rather than literally or precisely.

FIG. 1A is a schematic diagram of an exemplary embodiment of a neutron beam system.

FIG. 1B is a schematic diagram of another exemplary embodiment of a neutron beam system.

FIG. 2 is a cross-sectional view depicting an exemplary embodiment of a target assembly subsystem.

3A, 3B, and 3C are cross-sectional, front perspective, and back perspective views depicting an exemplary embodiment of a neutron generating target. 3A, 3B, and 3C are cross-sectional, front perspective, and back perspective views depicting an exemplary embodiment of a neutron generating target.

4A-4B are cross-sectional views depicting exemplary embodiments of neutron generating targets.

FIG. 5 is a cross-sectional view depicting an exemplary embodiment of a neutron generating target.

6A-6C are cross-sectional views depicting exemplary embodiments of neutron generating targets.

7A-7B are cross-sectional views depicting exemplary embodiments of neutron generating targets.

FIG. 8 is a graph depicting X-ray photoelectron spectroscopy (XPS) data experimentally collected from a sample piece.

FIG. 9 includes a series of top and bottom photographs depicting an exemplary embodiment of a target with a passivated region containing lithium fluoride.

FIGS. 10A-10C include a time series of top and bottom photographs depicting a bare lithium substrate (left) adjacent to an exemplary embodiment of a target (right).

FIG. 11 is a graph depicting XPS data experimentally collected from a sample piece.

Before this subject matter is described in detail, it is to be understood that this disclosure is not limited to particular embodiments described, as such may, of course, vary. It is a limitation, as the terminology used herein is for the purpose of describing particular embodiments only, and the scope of the disclosure will be limited only by the claims appended hereto. It should also be understood that this is not intended.

Neutron generating targets and other high energy devices or structures often have corrosive and/or mobile chemical components such as lithium. Exemplary embodiments of systems, devices, and methods for passivating or protecting these corrosive and/or mobile materials are described herein. For ease of discussion, materials that are intended to be passivated or protected may be referred to herein as target materials. The passivation region may be configured to hold or maintain the target material in place by inhibiting diffusion of the target material into (and completely through) the passivation region. can. The passivation region isolates the target material from chemicals in the surrounding environment, thereby preventing contaminants (e.g., air components such as nitrogen and oxygen or water components such as hydrogen and oxygen) and other undesired corrosion reactions. It may also be configured to protect the target material from.

The applications in which the target materials are used can vary widely. Exemplary embodiments of passivation for target materials in this wide variety of applications are described herein. A non-exhaustive list of applications includes: nuclear reactors for research or energy generation and commercialization, such as fusion and fission reactors; medical applications, such as medical diagnostic systems, medical imaging systems, or radiation therapy systems. , particle accelerators used for pathogen destruction in scientific tools, industrial or manufacturing processes (such as the production of semiconductor chips), modification of material properties (such as surface treatments), food irradiation, or medical sterilization; and cargo or containers. Imaging applications such as inspections.

For ease of explanation, many embodiments described herein are in the context of a radiation therapy system that uses lithium target materials as the neutron generating material in a neutron generating target configured for use in a BNCT. That's how it will be done. Embodiments can be used with other neutron generating materials such as beryllium (Be). Embodiments are not limited to neutron generation or BNCT applications.
(Exemplary BNCT application)

Turning to the figures in detail, FIG. 1A is a schematic diagram of an exemplary embodiment of a beam system 10 for use with embodiments of the present disclosure. In FIG. 1A, a beam system 10 includes a source 12, a low energy beamline (LEBL) 14, an accelerator 16 coupled to the low energy beamline (LEBL) 14, and a high energy beam extending from the accelerator 16 to a target 100. beam line (HEBL) 16. LEBL 14 is configured to transport a beam from source 12 to an input of accelerator 16, which in turn is configured to generate a beam by accelerating the beam transported by LEBL 14. HEBL 18 transports the beam from the output of accelerator 40 to target 100. Target 100 may be a structure configured to produce a desired result or modify the properties of the beam in response to a stimulus applied by the incident beam. Target 100 may be a component of system 10 or may be a workpiece prepared or manufactured, at least in part, by system 10.

FIG. 1B is a schematic diagram illustrating another exemplary embodiment of a neutron beam system 10 for use in boron neutron capture therapy (BNCT). Here, source 12 is an ion source and accelerator 16 is a tandem accelerator. Neutron beam system 10 includes a pre-accelerator system 20 that serves as a charged particle beam injector, a high voltage (HV) tandem accelerator 16 coupled to pre-accelerator system 20, and a target 100 (not shown) from tandem accelerator 16. ) extending to a neutron target assembly 200 housing a HEBL 18 . In this embodiment, target 100 is configured to generate neutrons in response to bombardment by protons of sufficient energy and may be referred to as a neutron generating target. Neutron beam system 10 and pre-accelerator system 20 can also be used for other applications, such as other examples thereof described herein, and are not limited to BNCT.

Pre-accelerator system 20 is configured to transport the ion beam from ion source 12 to an input (eg, input aperture) of tandem accelerator 16, and thus also functions as LEBL 14. Tandem accelerator 16 powered by a coupled high voltage power supply 42 can produce a proton beam with an energy generally equal to twice the voltage applied to accelerating electrodes positioned within accelerator 16. The energy level of the proton beam accelerates a beam of negative hydrogen ions from the input of the accelerator 16 to the innermost high potential electrode, robs each ion of two electrons, and then moves the resulting protons downstream with the same applied voltage. This can be achieved by accelerating.

The HEBL 18 is capable of transporting a proton beam from the output of the accelerator 16 to a target in a neutron target assembly 200, which is positioned at the end of a beamline branch 70 extending into the patient treatment room. It is being System 10 can be configured to direct the proton beam to any number of one or more targets and associated treatment areas. In this embodiment, the HEBL 18 includes three branches 70, 80, and 90 that may extend into three different patient treatment rooms, where each branch includes a target assembly 200 and a downstream beam forming It can be terminated at a device (not shown). The HEBL 18 includes a pump chamber 51, quadrupole magnets 52 and 72 to prevent beam defocus, dipole or bending magnets 56 and 58 to steer the beam into the treatment room, and beam correction. 53, diagnostic equipment such as current monitors 54 and 76, a fast beam position monitor 55 section, and a scanning magnet 74.

The design of the HEBL 18 depends on the configuration of the treatment facility (eg, one-story treatment facility configuration, two-story treatment facility configuration, etc.). The beam can be delivered to a target assembly 200 (eg, located near a treatment room) through the use of bending magnets 56. A quadrupole magnet 72 can then be included to focus the beam to a size at the target. The beam then passes through one or more scanning magnets 74, which direct it onto the target surface in a desired pattern (e.g., spiral, curved, stepped in rows and columns, combinations thereof, etc.). Provides lateral movement of the beam. Beam lateral movement can help achieve a smooth and uniform time-averaged distribution of the proton beam over the lithium target, preventing overheating and making neutron generation as uniform as possible within the lithium layer. can.

After entering scanning magnet 74, the beam can be delivered into a current monitor 76 that measures the beam current. Target assembly 200 can be physically separated from the HEBL volume using gate valve 77. The primary function of the gate valve is to isolate the vacuum volume of the beamline from the target during target loading and/or during replacing a spent target with a new one. In embodiments, the beam may not be bent 90 degrees by bending magnet 56; rather, it travels straight to the right in FIG. 1B and then enters quadrupole magnet 52, which is located in the horizontal beam line. The beam can subsequently be bent to the required angle by another bending magnet 58, depending on the building and room configuration. Otherwise, the bending magnet 58 may be replaced with a Y-shaped magnet to split the beam line into two directions for two different treatment rooms located on the same floor.

FIG. 2B is a cross-sectional drawing depicting an exemplary embodiment of the target assembly subsystem 200 of the neutron beam system 10 shown in FIG. 1B. In this embodiment, the neutron generating target 100 is enclosed between the cap 202 and a vacuum or near-vacuum interior region 210 of the HEBL 18. Arrow B indicates the direction of the charged particle (eg, proton) beam that first impinges on upstream surface 112. Cooling of target 100 can be accomplished on the opposite downstream side 114 from which the neutron beam exits target 100. The cap 202 is bolted to the HEBL 18 and thus provides both a vacuum-tight seal 206 between the target 100 and the vacuum region 210 of the HEBL 18 and a water-tight seal 205 between the target 100 and the coolant inlet 204 and outlet 208. can be provided.
(Exemplary Embodiment of Passivated Region)

FIG. 3A is a cross-sectional view depicting an exemplary embodiment of a passivated neutron generating target 100 for BNCT. 3B and 3C are perspective views of upstream side 112 and downstream side 114 of target 100, respectively. Target 100 includes a target material within region 110. Some examples of target materials are lithium (eg, naturally abundant lithium or lithium-7) and beryllium. At a location upstream (e.g., above) region 110, target 100 includes a passivated region 302 configured to protect region 110, such as by inhibiting diffusion, as described herein. include. Passivation region 302 and region 110 may have a variety of different shapes, including, for example, planar, concave, convex, round, spherical or hemispherical, conical, irregular, and/or any combination thereof. can be configured in

In this embodiment, region 110 is configured as a planar neutron generating layer, which is coupled to substrate structure 120 on a first (or upstream) surface 121 of substrate 120 . A proton beam propagating in direction B (e.g., from tandem accelerator 16 along HEBL 18 (not shown)) passes through passivation region 302 and then interacts with layer 110, producing neutrons and Then, the neutrons pass through substrate 120 and exit downstream 114 of target 100. The neutron generation process converts the target material (eg, lithium) into a radioactive isotope (eg, beryllium, 7Be).

Substrate 120 can be configured for heat removal to dissipate high energy levels of the incident proton beam. The passivation region 302 and the neutron generation layer 110 preferably generate protons relatively quickly after the proton energy falls below the nuclear reaction threshold for neutron formation (e.g., 1.88 MeV for lithium-7). It has a total thickness that allows it to exit layer 110. This avoids further energy dissipation in layer 110, which is inefficient and leads to heating of layer 110 without neutron production. The protons penetrate the neutron generating material layer 110 to the substrate 120 and dissipate their remaining energy in the substrate 120 or partially in the substrate 120 and partially in another component located downstream of the target 100. can do. Substrate 120 can be made from a material with high thermal conductivity, such as copper (Cu), copper-diamond powder composite, CVD diamond, etc., for example. Target 100 can include one or more materials to suppress blistering, such as a tantalum layer between layer 100 and substrate 120. The downstream side 114 of the substrate 120 can be actively cooled by coolant flow through channels 122 designed to remove heat (eg, about 25 kilowatts (kW) of heat output). Channel 122 can have a helical configuration as depicted in FIG. 3C or another configuration as desired.

The target material for layer 110 can be a highly mobile or diffusive material such as lithium. The passivation region 302 inhibits diffusion of the target material within the layer 110 in a downstream-to-upstream direction into (or through the region 302) (e.g., seals against, In region 302, the target material may come into contact with another substance or the surrounding environment. Suppression of diffusion of the target material can be accomplished by one or more different materials within one or more layers of region 302. In some exemplary embodiments, the passivated region 302 has a diffusion coefficient for the target material of 1×10 ⁻¹³ square centimeters per second (cm ² /s) or less, while in other embodiments the region 302 has a , 1×10 ⁻¹⁴ cm ² /sec or less, and in still other embodiments, region 302 has a diffusion coefficient for the target material of 1×10 ⁻¹⁵ cm ² /sec or less. can have a coefficient. Exemplary embodiments of passivation region 302, where the target material is lithium, have a diffusion coefficient for lithium of 5×10 ⁻¹⁴ cm ² /sec or less, and in some embodiments, 5×10 ⁻¹⁵ cm 2 /s or less. It can have a diffusion coefficient for lithium of less than or equal to cm ² /sec. All of the foregoing coefficients are measured at 25 degrees Celsius and are based on the properties of any one or more of the materials or layers of region 302 (e.g., layer 310 and/or layer 410) or the properties of region 302 as a whole. It can be. For ease of explanation, this property of inhibiting diffusion of the target material may be referred to herein as the target barrier property. In the embodiment of FIGS. 3A-3C, layer 310 is configured to exhibit this desired barrier property.

In embodiments employing lithium as the target material, this property may also be referred to as the lithium barrier property. Lithium barrier properties can be exhibited in the passivated region 302 by a variety of different materials. Examples of such materials that can be used with any and all embodiments described herein include lithium fluoride (LiF), lithium sulfide ( _Li2S ), or any other material that is thermodynamically stable with Li. is (or can include) one or more of the following: compounds, magnesium fluoride ( _MgF2 ), carbon (C), diamond-like carbon, (super) nanocrystalline diamond, or polymers such as parylene. Other materials known to inhibit lithium diffusion may also be used without departing from the scope of this disclosure. Similarly, these or other materials can be used for embodiments where the target material is different from lithium, such as, for example, beryllium, without departing from the scope of the present disclosure.

In neutron generation applications, materials exhibiting reactant barrier properties that also include neutron generation materials (e.g., lithium or beryllium) can provide additional benefits of neutron generation during use (e.g., in addition to the neutron generation layer). ). In embodiments where the neutron generating material is lithium, the material exhibiting lithium barrier properties may therefore be, by way of example, lithium fluoride and/or lithium sulfide. Lithium-containing materials such as lithium nitride (Li ₃ N), lithium oxide (Li ₂ O), and lithium hydroxide (LiOH) do not exhibit substantially low lithium diffusion coefficients and, in some embodiments, have lithium barrier properties. (eg, as layer 310). Preferably, the lithium barrier material does not directly contaminate or corrode lithium and is not (or does not include) a material such as aluminum or an alloy of aluminum. In some embodiments, the lithium barrier material is not beryllium or a combination of metals such as beryllium and aluminum.

In some embodiments, the target barrier material does not form a eutectic combination (a combination having a melting point less than the melting point of the constituent materials taken individually) with the target material. When the target material is lithium, some embodiments include combinations with lithium such as aluminum, silver, gold, bismuth, palladium, or zinc, or alloys of aluminum, silver, gold, bismuth, palladium, or zinc. Materials forming the crystal combination can be omitted.

Region 302 also includes an external supply of material (e.g., air, moisture, oxygen, nitrogen, carbon dioxide, hydrogen, or other gases) in an upstream to downstream direction into (or through) region 302 . from the surrounding environment, such as any one or a combination of substances). If such materials get into target 100, they can potentially contaminate or react with (eg, oxidize) the target material within layer 110. For ease of explanation, this property may be referred to herein as a peripheral barrier property. Ambient barrier properties can be exhibited in environments with normal atmospheric pressure (eg, 1 atmosphere (ATM)), higher pressure environments, or lower pressure environments (eg, vacuum or near vacuum). Peripheral barrier properties can be exhibited in passivated region 302 by a variety of different materials. Examples of such materials are one or more of aluminum, silver, gold, titanium, stainless steel, aluminum silicon (AlSi), molybdenum, tungsten, tungsten carbide, tantalum, platinum, or other contamination barrier materials. (or may contain it). Other materials known to inhibit or prevent the diffusion of contaminants in the target material may also be used without departing from the scope of this disclosure.

In some exemplary embodiments, the ambient barrier property is a gas permeability for oxygen, nitrogen, and carbon dioxide of 100 or less, preferably 3.1 or less (cubic centimeters (cc) x millimeters (mm) at 25 degrees Celsius) ))/(measured in square meters (m ² )×days×atmospheric pressure (atm)). In some exemplary embodiments, in addition to any of these gas permeabilities, the ambient barrier property is a water vapor transmission rate (WTVR) of 0.6 or less, more preferably 0.09 or less (100 degrees Fahrenheit and at 90% relative humidity (measured in grams (g) x mm)/(m ² x days).

The objective barrier properties and ambient barrier properties need not be permanent, but rather over a length of time that is practically effective for the particular application, which may vary as described herein (e.g., 1 can be robust enough to inhibit spread (for more than an hour, for more than a day, for more than a week, for more than a month). Embodiments of the passivated region 302 disclosed herein can be used to protect neutron generating materials for long periods of time, one month or more.

Passivated region 302 can be immediately adjacent to and in contact with layer 110, or can be separated by one or more other layers or regions. In the embodiment of FIGS. 3A-3C, the passivation region 302 is comprised of only one layer 310 (eg, lithium fluoride) that exhibits reactant barrier properties. Layer 310 can be further configured to exhibit ambient barrier properties (eg, lithium fluoride for short duration applications).

FIG. 4A is a cross-sectional view depicting another exemplary embodiment of a neutron generating target 100 with a passivated region 302. In this embodiment, region 302 includes a passivation layer 310 (positioned upstream of layer 110 as in the previous embodiment) and an additional passivation layer 310 positioned upstream of and adjacent to layer 310. layer 410. Layer 410 may be referred to as upstream layer 410 and layer 310 may be referred to as downstream layer 310. Upstream layer 410 can be disposed on the first upstream surface of downstream layer 310, which in turn can be disposed on the first upstream surface of layer 110. One or more additional layers or films may be present within region 302, such as an intervening layer described with respect to FIG. 4B.

In the embodiment of FIG. 4A, downstream layer 310 exhibits lithium barrier properties, inhibiting lithium in layer 110 from diffusing upward into layer 410. Layer 310 can be, for example, lithium fluoride or any of the other lithium barrier materials disclosed herein. The upstream passivation layer 410 exhibits ambient barrier properties, inhibiting the ingress and diffusion of externally supplied materials that could contaminate or corrode the lithium in the layer 110. Layer 410 can be, for example, aluminum or any of the other peripheral barrier materials described herein. Therefore, the double layer configuration of region 302 is such that layer 410 has good sealing or barrier properties but would otherwise corrode the lithium in layer 110 and reduce the effectiveness of the neutron generating capacity of the lithium. Enables things to be made of matter. Layer 310 acts as a non-reactive barrier to inhibit the migration of lithium in contact with layer 410, thus minimizing any damage or otherwise undesirable reactions. Such a configuration is particularly desirable when the target material is highly mobile, as is the case with lithium.

In some exemplary embodiments, the thickness of passivation region 302 (e.g., the thickness of layer 310 when present alone, or the combined thickness of layers 310 and 410) Although not greater than 3 microns in BNCT applications to minimize energy reduction, region 302 is not so limited. In other embodiments, region 302 does not exceed 10 microns in thickness, and in still other embodiments, region 302 does not exceed 50 microns in thickness. The particular thickness selected depends on the application, such as the accelerating voltage or other potential difference. For regions 302 with multiple layers (eg, 310 and 410), the thickness of each layer depends on the specific application and the desired degree of diffusion suppression. Therefore, a wide range of thicknesses are within the scope of this disclosure.

FIG. 4B is a cross-sectional drawing depicting another exemplary embodiment of a neutron generating target 100 with multilayer passivation. Here, region 302 includes three passivation layers: a downstream layer 310, an upstream layer 410, and an intermediate layer 450 located between layers 310 and 410. Intermediate layer 450 may promote adhesion between layers 310 and 410, assist in stress relief (eg, as a polymer, shape memory alloy, etc.), or perform other functions. Intermediate layer 830 can also prevent diffusion of materials between layer 310 and layer 410. In some embodiments, the layers are such that a downstream layer 310 is deposited on the upstream surface of the neutron generating material 110, an intermediate layer 450 is deposited on the upstream surface of the layer 310, and an upstream layer 410 is deposited on the upstream surface of the neutron generating material 110. They can be deposited sequentially, such as being deposited on the upstream surface of layer 450. Layers 310, 410, and/or 450 are formed through any applicable manufacturing technique, such as by deposition (e.g., chemical vapor deposition), sputtering, or the use of adhesives, mechanical force, or other mechanisms for attachment. (eg, on layer 110). The desired thickness of intermediate layer 450 depends on the specific application and environment for the neutron generating target. Therefore, various thicknesses are within the scope of this disclosure.

5-7B will be used to describe additional exemplary embodiments involving passivation. These embodiments have either a single passivation layer within region 302 (FIG. 7A) or two passivation layers within region 302. However, the embodiments of FIGS. 5-7B can each be configured with one, two, three, or more passivation layers within region 302.

FIG. 5 is a cross-sectional view depicting an additional exemplary embodiment of neutron generating target 100 in which passivation coats both the top and sides of neutron generating layer 110. Here, the passivation region 302 overlies the top upstream surface 111A of the neutron generating layer 110 and the lateral sides 111B and 111C (e.g., the same side, as in the case of the round target 100). layers 310 and 410 deposited (or otherwise positioned) over (obtaining). Both layers 310 and 410 terminate at a location downstream of (eg, below) downstream surface 121. In this embodiment, lateral sides 111B and 111C of layer 110 are coplanar with the sides of substrate 120, but that may vary. Additionally, although passivation layers 310 and 410 are depicted as being thinner as they extend from upstream surface 111A to sides 111B and 111C, their thickness can be maintained across all surfaces (e.g. , even or uniform coverage).

6A-6C are cross-sectional views depicting additional exemplary embodiments of target 100 with passivation. In these embodiments, the substrate 120 includes sidewalls 602B and 602C that partially define an interior volume, such as a recess or cavity, in which the neutron generating material 110 is deposited (or otherwise located). Encapsulate. The downstream surface of material 110 is coupled to the upstream surface 121 of the recess of substrate 120, such as through adhesive, interference fit, or other manner of attachment. Recesses within substrate 120 can be machined or etched into substrate 120. Substrate 120 may (or alternatively) be a multi-piece construction, with relatively taller sidewall portions 602B (adjacent to 111B) and 602C (adjacent to 111C) attached to central portion 602D and recessed. Form. In these embodiments, side protection is primarily provided to layer 110 by substrate 120.

In the embodiment of FIG. 6A, passivation region 302 includes two passivation layers 310 and 410, both of which are also located within recesses within substrate 120. In some embodiments, the most distal upstream surface 411 of region 302 (eg, of layer 402) can be coplanar with the most distal upstream surface 611 of substrate 120, as shown in FIG. 6A. In the embodiment of FIG. 6B, layer 110 is again placed within the recess and passivation region 302 again includes two passivation layers 310 and 410. However, in this example, both passivation layers 310 and 410 are located above the recesses in layer 110 and substrate 120. Here, the farthest upstream surface 111A of layer 110 is coplanar with the farthest upstream surface 611 of substrate 120, although embodiments may vary. In the embodiment of FIG. 6C, layer 110 and downstream passivation layer 310 are positioned within the recess, while upstream passivation layer 410 is located above layer 310 and the recess in substrate 120. Here, the farthest upstream surface 311 of layer 310 is coplanar with the farthest upstream surface 611 of substrate 120, but again, embodiments may vary. In embodiments with an intermediate layer 450, the layer 450 is within the recess with layers 310 and 410 (FIG. 6A), over the recess with layers 310 and 410 (FIG. 6B), or within the recess or It can be positioned anywhere above the recess (as allowed in the embodiment of FIG. 6C).

7A and 7B are cross-sectional views depicting additional exemplary embodiments of neutron generating target 100. In the embodiment of FIG. 7A, layer 110 is located on upstream surface 611 of substrate 120. Passivation region 302 includes layer 310 positioned above layer 110 such that all surfaces 111A, 111B, and 111C are covered. In the embodiment of FIG. 7B, region 302 includes layer 310 positioned above layer 110 such that all surfaces 111A, 111B, and 111C are coated and all surfaces of layer 310 are coated. and a layer 410 positioned above layer 310. In other words, layer 310 encapsulates layer 110 and layer 410 encapsulates both layers 310 and 110. These embodiments can be relatively easily manufactured using, for example, sequential deposition steps for each of the layers (eg, 110, 310, and 410) without the formation of recesses.

In the embodiments of FIGS. 3A and 4A-7B, the various layers (e.g., layers 110, 310, 410, and/or 450) are not to scale with respect to each other and with respect to the thickness of substrate 120. The emphasis is instead on the relative position of the layers with respect to each other. Additionally, the layers (e.g., layers 110, 310, 410, and/or 450) may have a rectangular side profile with sharp edges (e.g., FIGS. 3A, 4A, 4B, and 6A-6C), or a spherical profile with rounded edges. For ranges shown as having various cross-sectional profiles, such as shaped profiles (e.g., FIGS. 5 and 7A-7B), or defined linear boundaries between layers, those representations are by way of example only and may vary depending on the particular application. may vary according to needs. Each embodiment described herein can be constructed of layers having any cross-sectional profile, hybrid or deterministic linear or non-linear boundaries, and/or any combination thereof.

Among other benefits, example embodiments described herein can generate neutrons (e.g., for BNCT applications) from a production location (e.g., a laboratory space, a drying room, a glove box, or other). The transport of the target material (eg, lithium) to the working environment (for the purpose of processing) can be dramatically simplified. In applications where the target material is a plasma-facing component, the passivation layer upstream (e.g., most upstream) of the passivation region may be configured such that it interacts with the plasma without contaminating the plasma. . Alternatively, the upper passivation layer can be configured to burn out during initial plasma interaction or chamber wall conditioning. In such embodiments, the target material remains exposed to the plasma for interaction purposes, and the one or more passivation layers provide protection for transport of the target material from the production site to the working environment. It would have been successful in providing the coating.
(Experimental result)

FIG. 8 is a graph depicting data experimentally collected from a sample piece in which high purity aluminum was deposited onto clean lithium metal, which was then exposed to air. X-ray photoelectron spectroscopy (XPS) was used to collect the spectral data depicted here, which shows the surface (within a few nanometers) of deposited aluminum two weeks after the original aluminum deposition. The composition of the above species is shown. These results indicate that no aluminum remained on the surface at this point. For this sample, it was concluded that lithium easily diffused through the surface layer of aluminum and then reacted with components in the air. Aluminum may also have been diffused into the underlying lithium layer. In embodiments where the target material is lithium or another highly mobile species, the passivation region 302 preferably allows lithium to pass through the passivation region to other components (e.g., oxygen, water, and Carbon dioxide) has the ability to substantially suppress and even prevent its diffusion to locations where it can react without carbon dioxide.

FIG. 9 includes a series of looking down photographs (from upstream to downstream) depicting an exemplary embodiment of a target 100 configured as depicted in the cross-sectional view of FIG. 7A, primarily from naturally abundant lithium. The neutron generating layer 110 consisting of is covered by a passivation region 302 with only one passivation layer 310, which layer 310 consists of lithium fluoride. In this example, layer 310 has a thickness of 500 nm. Target 100 was removed from the inert gas atmosphere in the glove box and placed in an ambient laboratory setting with normal atmosphere having a humidity level of 50%. Each photo was taken at a specific time, measured from approximately the first moment (time zero) when target 100 was first exposed to the atmosphere within the laboratory setting. Time zero is the photo at zero minutes (0 minutes) labeled on the top left, the second photo from the left in the top row is taken 30 seconds (0.5 minutes) after time zero, and the photo on the top The photo in the middle of the row is taken one minute (1 minute) after time zero, and so on until the last photo is taken 170 minutes after time zero (bottom row, far right).

Naturally abundant lithium typically reacts almost immediately with the surrounding atmosphere (e.g., 20-60% relative humidity) to form a dark-colored lithium nitride within seconds (e.g., 10-30 seconds) of atmospheric exposure. (Li ₃ N) may form a top coat. Here, at time zero, the lithium visible through the LiF topcoat appears shiny (same appearance as in the glove box) and shows little or no reaction between the lithium and its surroundings. After a few minutes, the color of the target 100 changes to yellow (e.g., 2 minutes), then to brown (e.g., 4 minutes), and then finally to dark purple or black after 1 or 2 hours, indicating that the lithium - Li ₃ N formation on the LiF interface 311 is shown. Thus, the LiF passivation layer 310 substantially retards lithium contamination, thereby providing a substantial improvement over targets without passivation and those with only an aluminum passivation layer as described with respect to FIG. brings about improvements.

10A-10C include a series of looking down photographs (from upstream to downstream) depicting a bare lithium substrate 900 (left) adjacent to an exemplary embodiment of a target 100 (right). Substrate 900 includes a copper substrate with a bare coating of naturally abundant lithium and has no passivated regions. Lithium is available to freely react with the surrounding atmosphere. The target 100 is configured as depicted in the cross-sectional view of FIG. It is covered by region 302. Cooling channels were omitted. Layer 310 consists of LiF with a thickness of 900 nm and layer 410 consists of aluminum with a thickness of 400 nm.

Both samples were removed from the inert gas atmosphere in the glove box and placed in an ambient laboratory setting with normal atmosphere with 50% humidity. The photograph of FIG. 10A was taken one minute after the approximate moment that target 100 and substrate 900 were first exposed to air within a laboratory setting. The photo in FIG. 10B was taken 3 minutes after the first exposure and the photo in FIG. 10C was taken 125 minutes after the first exposure. The bare lithium substrate 900 reacted almost immediately with the surrounding atmosphere, changing color already in 1 minute, turning a darker shade of purple in 3 minutes, and finally turning black in 125 minutes. Conversely, target 100 shows little or no discoloration even after 125 minutes. The absence of lithium discoloration was subsequently confirmed by inspection upon removal of the aluminum layer 410. These results, when considered in combination with the results of FIGS. 8 and 9, demonstrate that the bilayer passivated region 302 sufficiently protects the lithium layer 110 from contamination such as nitride formation even after 2 hours of exposure. Indicates that protection is provided. In other words, the LiF layer 310 substantially inhibited lithium from diffusing upstream through the layer 310 and the aluminum layer 410 substantially inhibited atmospheric reactants from diffusing downstream through the layer 410. .

FIG. 11 is a graph depicting experimentally collected data from an exemplary target 100 configured similarly to that described with respect to FIGS. 10A-10C, in which the naturally abundant layer of lithium is 310 (900 nm thick), the LiF layer 310 was then coated with an aluminum layer 410 (400 nm thick). The target was then exposed to air for several days. X-ray photoelectron spectroscopy (XPS) was used to collect the spectral data depicted in FIG. 11. Unlike the results of FIG. 8, where no aluminum remained on the surface of the aluminum coating, the results here show that the surface composition of the aluminum layer 410 still includes aluminum. This means that although some lithium is present on the surface, the lithium does not migrate to the aluminum surface where it would otherwise react and hide the aluminum, as occurred in the example of Figure 8. It is shown that the LiF layer 310 was substantially blocked.
(Exemplary Embodiment of Passivation Region Thickness)

Tables 1-4 facilitate description of the thickness characteristics of several embodiments of passivation region 302 used with an exemplary BNCT application in which a proton beam collides with a target lithium layer on a substrate and produces neutrons. Provide modeled values for Neutron generating targets are typically not suitable for use with thick passivation regions overlying the neutron generating material. This is because a thick passivated region reduces the energy of the incident protons and reduces the effectiveness of neutron generation.

Table 1 illustrates the range of incident proton particles (sometimes referred to as the stopping range) in naturally abundant lithium (approximately 92% lithium-7) for several proton energies. In the right column, the variable "depth to threshold" is listed, indicating that the average proton is in the material before it decelerates to the threshold energy (approximately 1.88 MeV) for the 7Li(p,n)7Be reaction. represents the distance traveled inside. After a proton is decelerated beyond this threshold energy, it can no longer produce neutrons. For example, for a proton energy of 2.50 megaelectron volts (MeV), a high-energy proton is incident on the lithium material and then travels approximately 90 microns through the lithium until it decelerates to a threshold energy. In this example, if the lithium thickness is less than 90 microns (μm), neutron yield is reduced and the lithium material is not utilized most efficiently. It is practically desirable to have a sufficiently thick lithium layer with respect to the neutron production target, but not so thick (e.g., 200 μm) that the drop in proton energy below the threshold dissipates excess heat in the lithium.

In embodiments with a protective coating over the lithium, the protective coating will further decelerate the protons. Table 2 shows the proton range for the same incident protons as in Table 1, but for the data in Table 2, a protective coating consisting of a 1 micron thick layer of lithium fluoride (LiF) is naturally abundant. Lithium has been added to the top.

For a proton incident energy of 2.5 MeV, a 1 micron thick LiF layer slows the protons by 0.03 MeV (2.5 MeV - 2.47 MeV). This slightly reduces the depth to threshold by about 4.5 microns.

Table 3 is associated with an embodiment having a 1 micron thick downstream passivation layer 310 (LiF) and a 0.5 micron thick upstream passivation layer 410 of aluminum over the underlying lithium layer. Illustrating the proton range. This configuration is similar to that described with respect to FIGS. 7 and 10.

Table 3 illustrates that a 1.5 micron thick bilayer passivation region does not slow down protons much. Because the passivation region with multiple passivation layers is thin, no significant incident particle energy loss is experienced within the region.

In contrast, if the passivation region is relatively thick, the proton energy is significantly reduced, making it difficult for practical neutron generation devices to accelerate the particles to higher energies. Not necessarily desirable. Table 4 illustrates how a relatively thick (10 micron) protective layer of Parylene C performs when placed over naturally abundant lithium. Parylene C is a widely used polymer consisting mostly of low-Z elements and is used to passivate electronic devices because Parylene C protects from moisture.

In Table 4, for the same energy of 2.50 MeV, a 10 micron layer of parylene C slows down protons by about 0.20 MeV, thus reducing the depth to threshold by almost 30 MeV compared to bare lithium (Table 1). % decrease, further illustrating the dependence of the depth to the threshold on the thickness of the passivated region. Most metal passivation of comparable thickness will decelerate protons more than polymeric parylene C.

The passivated regions of the embodiments described herein can form relatively thin passivated coatings. The ideal thickness of passivated region 302 depends on the particular application, and it may vary as described herein. For example, in some embodiments, the thickness of the entire passivation region 302 (measured from upstream to downstream along the beam axis (see, e.g., number 303 in FIGS. 3A, 4A, and 4B)) is 100 It is less than a micron. In some embodiments, the thickness of passivated region 302 is 50 microns or less. In some applications, such as BNCT, an even thinner passivation region 302 is desirable, but not required. For example, in these and other embodiments, the thickness of the passivated region 302 is 10 microns or less, or in some embodiments the thickness of the passivated region 302 is 5 microns or less, or in some other embodiments, the thickness of the passivated region 302 is 3 microns or less, and in some other embodiments the thickness of the passivated region 302 is 1 micron or less. .

The thickness of the target material can be as desired to meet the needs of the application. For BNCT applications, the desired thickness may depend on the incident proton energy and may range, for example, from 10 microns to 300 microns. In an exemplary embodiment where the energy of the incident proton beam is between 1.88 MeV and 3 MeV, the thickness of the lithium layer may be between 10 and 200 microns, and in an exemplary embodiment where the energy of the incident proton beam is between 2.25 MeV and 2.75 MeV. In a typical embodiment, the thickness of the lithium layer can be between 40 and 150 microns. In one exemplary embodiment, the lithium layer has a thickness of 40-150 microns and a bilayer passivation region 302 is positioned over it. The downstream layer 310 may be lithium fluoride and the upstream layer 410 may be a metal such as aluminum, titanium, stainless steel, alloys thereof, etc. The thickness of region 302 can be according to any of the embodiments described herein. In one exemplary embodiment, layer 310 has a thickness in the range of 200-400 nm and layer 410 has a thickness in the range of 500-800 nm.

In some exemplary embodiments, passivated region 302 (eg, all or a portion thereof, such as layers 310, 410, 450, etc.) can be removed during operation of the system in which it is installed. For example, in a BNCT application, the incidence of a particle beam on the passivated region 302 can cause the region 302 to be removed (eg, ablated or burned) from the target 100 during operation. The removal may be the result of an increase in temperature within region 302 as a result of the high energy particle beam. The resulting neutron generating reaction can also promote this decomposition of region 302. Removal of region 302 can increase the efficiency of neutron generation by neutron generation layer 110 by reducing the energy loss experienced by incoming particles slowing through passivated region 302. The particle beam may be moved across the target surface (e.g., rasterized) such that all or a portion of region 302 is at a relatively highest level of incidence of the particle beam on the target (e.g., duration), can be removed over a small area of the target's surface.

Embodiments described herein may also find applicability in battery design and manufacturing. The rapidly developing lithium battery industry suffers from lithium's limited sensitivity to humid atmospheres. The embodiments described herein can be applied when the device to be protected or passivated is a metallic lithium anode of a battery. Embodiments can simplify the fabrication and reduce the cost of metallic lithium anodes that are stable in ambient atmosphere (eg, air) and free of dendrites.

Various aspects of the present subject matter are described below in review of and/or as a supplement to previously described embodiments, with emphasis here on the interrelationship and compatibility of the embodiments described below. ing. In other words, emphasis is placed on the fact that each feature of the embodiments may be combined with any and all other features, unless explicitly stated otherwise or where logically impossible.

In various embodiments, the neutron generating target includes a substrate, a neutron generating region positioned over the substrate, and a passivation region positioned over the neutron generating region. In some of these embodiments, the neutron generation region includes a target material configured to generate neutrons, and the passivation region includes a target material configured to generate neutrons, and the passivation region includes a target material configured to generate neutrons. configured to seal.

In some of these embodiments, the passivated region has a diffusion coefficient with respect to the target material of 1×10 ⁻¹³ square centimeters per second (cm ² /s) or less. In some of these embodiments, the passivated region has a diffusion coefficient with respect to the target material of 1×10 ⁻¹⁴ cm ² /sec or less. In some of these embodiments, the passivated region has a diffusion coefficient with respect to the target material of 1×10 ⁻¹⁵ cm ² /sec or less.

In some of these embodiments, the target material is lithium. In some of these embodiments, the passivated region has a diffusion coefficient for lithium of 5×10 ⁻¹⁴ cm ² /sec or less.

In some of these embodiments, the target material is lithium. In some of these embodiments, the passivated region has a diffusion coefficient for lithium of 5×10 ⁻¹⁵ cm ² /sec or less.

In some of these embodiments, the passivation region includes lithium fluoride.

In some of these embodiments, the passivation region comprises lithium fluoride, lithium sulfide, magnesium fluoride, carbon (C), diamond-like carbon, (super)nanocrystalline diamond, or a polymer.

In some of these embodiments, the passivation region includes lithium. In some of these embodiments, the passivation region does not include lithium nitride, lithium oxide, or lithium hydroxide.

In some of these embodiments, the passivation region includes a layer in contact with the target material. In some of these embodiments, the layer does not include aluminum or beryllium.

In some of these embodiments, the passivated region has a thickness of 10 microns or less.

In some of these embodiments, the passivated region has a thickness of 3 microns or less.

In some of these embodiments, the target is configured for use in boron neutron capture therapy (BNCT) procedures.

In some of these embodiments, the target is configured to generate neutrons when exposed to a proton beam having an energy of 1.88 to 3.0 megaelectronvolts (MeV).

In some of these embodiments, the passivation region is configured to be removed during operation.

In some of these embodiments, the target material includes lithium.

In some of these embodiments, the passivated region does not include a eutectic combination of the target material and another material.

In various embodiments, a neutron generating target includes a substrate, a neutron generating region positioned over the substrate and including a target material configured to generate neutrons, and a neutron generating region positioned over the neutron generating region. and a passivation region including a downstream layer and an upstream layer. In some of these embodiments, the downstream layer is configured to seal against diffusion of the target material into the passivated region.

In some of these embodiments, the downstream layer has a diffusion coefficient with respect to the target material of 1×10 ⁻¹³ square centimeters per second (cm ² /s) or less. In some of these embodiments, the downstream layer has a diffusion coefficient with respect to the target material of 1×10 ⁻¹⁴ cm ² /sec or less. In some of these embodiments, the downstream layer has a diffusion coefficient with respect to the target material of 1×10 ⁻¹⁵ cm ² /sec or less.

In some of these embodiments, the target material is lithium. In some of these embodiments, the downstream layer has a diffusion coefficient for lithium of 5×10 ⁻¹⁴ cm ² /sec or less.

In some of these embodiments, the target material is lithium. In some of these embodiments, the downstream layer has a diffusion coefficient for lithium of 5×10 ⁻¹⁵ cm ² /sec or less.

In some of these embodiments, the downstream layer includes lithium fluoride.

In some of these embodiments, the downstream layer comprises lithium fluoride, lithium sulfide, magnesium fluoride, carbon (C), diamond-like carbon, (super)nanocrystalline diamond, or a polymer.

In some of these embodiments, the downstream layer includes lithium. In some of these embodiments, the downstream layer does not include lithium nitride, lithium oxide, or lithium hydroxide.

In some of these embodiments, the downstream layer does not include aluminum or beryllium.

In some of these embodiments, the upstream layer is configured to seal against diffusion of ambient materials into the passivated region.

In some of these embodiments, the upstream layer is configured to seal against diffusion of materials from the atmosphere into the passivated region.

In some of these embodiments, the upstream layer is configured to seal against diffusion of oxygen, nitrogen, and water into the passivated region.

In some of these embodiments, the upstream layer is configured to seal against diffusion of ambient materials that contact the downstream layer through the upstream layer of the passivation region.

In some of these embodiments, the upstream layer includes aluminum, titanium, platinum, nickel, steel, silver, gold, stainless steel, aluminum silicon, molybdenum, tungsten, tungsten carbide, and/or tantalum.

In some of these embodiments, the upstream layer has a gas permeability for oxygen, nitrogen, and carbon dioxide of 100 or less, measured in (cubic centimeters x millimeters)/(square meters x days x atmospheres).

In some of these embodiments, the upstream layer has a gas permeability for oxygen, nitrogen, and carbon dioxide of 3.1 or less, measured in (cubic centimeters x millimeters)/(square meters x days x atmospheres). have

In some of these embodiments, the upstream layer has a water vapor transmission rate (WTVR) measured in (grams x millimeters)/(square meters x days) of 0.6 or less.

In some of these embodiments, the upstream layer has a water vapor transmission rate (WTVR) measured in (grams x millimeters)/(square meters x days) of 0.09 or less.

In some of these embodiments, the upstream layer is in contact with the downstream layer.

In some of these embodiments, the passivation region includes an intermediate layer between the upstream and downstream layers.

In some of these embodiments, the passivated region has a thickness of 10 microns or less.

In some of these embodiments, the passivated region has a thickness of 3 microns or less.

In some of these embodiments, the target is configured for use in boron neutron capture therapy (BNCT) procedures.

In some of these embodiments, the target is configured to generate neutrons when exposed to a proton beam having an energy of 1.88 to 3.0 megaelectronvolts (MeV).

In some of these embodiments, at least a portion of the passivation region is configured to be removed during operation.

In some of these embodiments, the target material includes lithium.

In various embodiments, a method of manufacturing a target for boron neutron capture therapy includes applying a neutron generating region to a substrate and applying a passivation region over the neutron generating region. . In some of these embodiments, the neutron generation region includes a target material configured to generate neutrons, and the passivation region includes a target material configured to generate neutrons, and the passivation region includes a target material configured to generate neutrons. configured to seal.

In some of these embodiments, the layer downstream of the passivation region is configured to seal against diffusion of the target material into the passivation region.

In some of these embodiments, the method further includes applying an upstream layer of passivation region over the downstream layer. In some of these embodiments, the upstream layer contacts the downstream layer and/or the downstream layer contacts the neutron generating region.

In some of these embodiments, the neutron generation region and passivation region are configured according to any of the previously described embodiments.

In some of these embodiments, the neutron generation region and passivation region are configured according to any of the previously described embodiments.

In various embodiments, a method of generating neutrons includes applying a particle beam to a target such that particles from the particle beam traverse a passivation region and impact a neutron generating region of the target, generating neutrons. including doing. In some of these embodiments, the passivation region is configured to seal against diffusion of material of the neutron generating region into the passivation region. In some of these embodiments, the method further includes continuing to apply the particle beam to the target such that at least a portion of the passivated region is removed.

In some of these embodiments, the target is configured according to any of the previously described embodiments.

In some of these embodiments, the passivation region includes an upstream layer and a downstream layer. In some of these embodiments, both the upstream and downstream layers are removed by continued application of the particle beam within the target area.

In some of these embodiments, the method is performed as part of a boron neutron capture therapy (BNCT) procedure.

In various embodiments, the targeting device includes a substrate including a recess, a neutron generating region within the recess of the substrate, and a passivation region positioned over the neutron generating region. In some of these embodiments, the passivation region includes an upstream layer and a downstream layer. In some of these embodiments, the downstream layer is located within the recess.

In some of these embodiments, the upstream layer is located within the recess. In some of these embodiments, the substrate includes sidewalls adjacent the recess. In some of these embodiments, the downstream layer does not extend over the upstream surface of the sidewall.

In some of these embodiments, the upstream layer does not extend over the upstream surface of the sidewall.

In some of these embodiments, the upstream layer extends over the upstream surface of the sidewall.

In some of these embodiments, the target is configured according to any of the previously described embodiments.

In various embodiments, the targeting device includes a substrate and a neutron generating region positioned over the substrate. In some of these embodiments, the neutron generating region includes an upstream surface and a sidewall surface. In some of these embodiments, the targeting device further includes a passivation region positioned over the upstream and sidewall surfaces of the neutron generating region.

In some of these embodiments, the passivation region and the substrate enclose the neutron generating region.

In some of these embodiments, the target is configured according to any of the previously described embodiments.

In various embodiments, the device includes a substrate, a first region comprising lithium positioned over the substrate, and a passivation region positioned over the first region. In some of these embodiments, the passivation region is configured to seal against diffusion of lithium into the passivation region.

In some of these embodiments, the first material is lithium. In some of these embodiments, the passivated region has a diffusion coefficient for lithium of 5×10 ⁻¹⁴ cm ² /sec or less.

In some of these embodiments, the first material is lithium. In some of these embodiments, the passivated region has a diffusion coefficient for lithium of 5×10 ⁻¹⁵ cm ² /sec or less.

In some of these embodiments, the passivation region includes lithium fluoride.

In some of these embodiments, the passivation region comprises lithium fluoride, lithium sulfide, magnesium fluoride, carbon (C), diamond-like carbon, (super)nanocrystalline diamond, or a polymer.

In some of these embodiments, the passivation region includes lithium. In some of these embodiments, the passivation region does not include lithium nitride, lithium oxide, or lithium hydroxide.

In some of these embodiments, the passivated region has a thickness of 100 microns or less.

In some of these embodiments, the passivated region has a thickness of 50 microns or less.

In various embodiments, the device includes a substrate, a first region positioned over the substrate and comprising lithium, a downstream layer and an upstream layer positioned over the first region. and a passivated region. In some of these embodiments, the downstream layer is configured to seal against diffusion of lithium into the passivated region.

In some of these embodiments, the downstream layer has a diffusion coefficient for lithium of 5×10 ⁻¹⁴ cm ² /sec or less.

In some of these embodiments, the downstream layer has a diffusion coefficient for lithium of 5×10 ⁻¹⁵ cm ² /sec or less.

In some of these embodiments, the downstream layer includes lithium fluoride.

In some of these embodiments, the downstream layer comprises lithium fluoride, lithium sulfide, magnesium fluoride, carbon (C), diamond-like carbon, (super)nanocrystalline diamond, or a polymer.

In some of these embodiments, the downstream layer includes lithium. In some of these embodiments, the downstream layer does not include lithium nitride, lithium oxide, or lithium hydroxide.

In some of these embodiments, the downstream layer does not include aluminum or beryllium.

In some of these embodiments, the upstream layer is configured to seal against diffusion of ambient materials into the passivated region.

In some of these embodiments, the upstream layer is configured to seal against diffusion of materials from the atmosphere into the passivated region.

In some of these embodiments, the upstream layer is configured to seal against diffusion of oxygen, nitrogen, and water into the passivated region.

In some of these embodiments, the upstream layer is configured to seal against diffusion of ambient materials that contact the downstream layer through the upstream layer of the passivation region.

In some of these embodiments, the upstream layer has a gas permeability for oxygen, nitrogen, and carbon dioxide of 100 or less, measured in (cubic centimeters x millimeters)/(square meters x days x atmospheres).

In some of these embodiments, the upstream layer has a gas permeability for oxygen, nitrogen, and carbon dioxide of 3.1 or less, measured in (cubic centimeters x millimeters)/(square meters x days x atmospheres). have

In some of these embodiments, the upstream layer has a water vapor transmission rate (WTVR) measured in (grams x millimeters)/(square meters x days) of 0.6 or less.

In some of these embodiments, the upstream layer has a water vapor transmission rate (WTVR) of 0.09 or less, measured in (grams x millimeters)/(square meter x day).

In some of these embodiments, the upstream layer includes aluminum, titanium, platinum, nickel, steel, silver, gold, stainless steel, aluminum silicon, molybdenum, tungsten, tungsten carbide, and/or tantalum.

In some of these embodiments, the upstream layer is in contact with the downstream layer.

In some of these embodiments, the passivation region includes an intermediate layer between the upstream layer and the downstream layer.

In some of these embodiments, the passivated region has a thickness of 100 microns or less.

In some of these embodiments, the passivated region has a thickness of 50 microns or less.

In various embodiments, a neutron beam system includes an accelerator and a beamline extending from the accelerator to a neutron generation target configured according to any of the embodiments described above.

All features, elements, components, functions, and steps described with respect to any embodiment provided herein are freely combinable and substitutable with those from any other embodiments. Note that it is intended to be When a feature, element, component, function, or step is described with respect to only one embodiment, unless explicitly stated otherwise, that feature, element, component, function, or step It is to be understood that it may be used in conjunction with any other features described herein. This paragraph therefore provides that features from different embodiments may be combined at any time, even if the following description does not explicitly state that such combinations or substitutions are possible in a particular case. , antecedents for the introduction of claims combining or substituting features, elements, components, functions, and steps from one embodiment with those of another embodiment. and serve as a writing aid. An explicit enumeration of all possible combinations and substitutions would be unduly burdensome, especially given that the permissibility of all such combinations and substitutions would be readily recognized by those skilled in the art. It is explicitly recognized that

As used in this specification and the appended claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise.

While the embodiments are susceptible to various modifications and alternative forms, specific examples thereof are shown in the drawings and herein described in detail. However, these embodiments are not limited to the particular forms disclosed; to the contrary, these embodiments are intended to cover all modifications, equivalents, and alternatives falling within the spirit of this disclosure. Please understand that this covers the following. Additionally, any feature, feature, step, or element of the embodiments and negative limitations that define the scope of the claimed invention by any feature, feature, step, or element not within the scope of the embodiments are recited in the claim. or may be added to.

Claims (93)

A neutron generating target, the neutron generating target comprising:
a substrate;
a neutron generating region positioned over the substrate;
a passivation region positioned over the neutron generation region;
The neutron generation region comprises a target material configured to generate neutrons, and the passivation region is configured to seal against diffusion of the target material into the passivation region. neutron-generating target. The target of claim 1, wherein the passivated region has a diffusion coefficient with respect to the target material of 1×10 ⁻¹³ square centimeters per second (cm ² /s) or less. 2. The target of claim 1, wherein the passivated region has a diffusion coefficient with respect to the target material of 1 x ^10-14 cm2 ^/ sec or less. 2. The target of claim 1, wherein the passivated region has a diffusion coefficient for the target material of less than or equal to 1 x ^10-15 cm2 ^/ sec. The target of claim 1, wherein the target material is lithium and the passivated region has a diffusion coefficient for lithium of 5×10 ⁻¹⁴ cm ² /sec or less. 2. The target of claim 1, wherein the target material is lithium and the passivated region has a diffusion coefficient for lithium of 5×10 ⁻¹⁵ cm ² /sec or less. A target according to any of claims 1-6, wherein the passivation region comprises lithium fluoride. 7. The passivating region comprises lithium fluoride, lithium sulfide, magnesium fluoride, carbon (C), diamond-like carbon, (hyper)nanocrystalline diamond, or a polymer. Targets listed. A target according to any of claims 1-6, wherein the passivation region comprises lithium and no lithium nitride, lithium oxide or lithium hydroxide. The target of any one of claims 1-6, wherein the passivation region comprises a layer in contact with the target material, the layer comprising neither aluminum nor beryllium. A target according to any preceding claim, wherein the passivated region has a thickness of 10 microns or less. A target according to any preceding claim, wherein the passivated region has a thickness of 3 microns or less. 13. A target according to any of claims 1-12, configured for use in a boron neutron capture therapy (BNCT) procedure. 14. The target of claim 13, configured to generate neutrons when exposed to a proton beam having an energy of 1.88 to 3.0 megaelectronvolts (MeV). 15. A target according to any preceding claim, wherein the passivated region is configured to be removed during operation. A target according to any of claims 1-15, wherein the target material comprises lithium. 17. A target according to any preceding claim, wherein the passivated region does not comprise a eutectic combination of the target material and another material. A neutron generating target, the neutron generating target comprising:
a substrate;
a neutron generation region comprising a target material positioned over the substrate and configured to generate neutrons;
a passivation region positioned over the neutron generation region and comprising a downstream layer and an upstream layer;
The downstream layer is configured to seal against diffusion of the target material into the passivated region. 19. The target of claim 18, wherein the downstream layer has a diffusion coefficient with respect to the target material of 1×10 ⁻¹³ square centimeters per second (cm ² /s) or less. 19. The target of claim 18, wherein the downstream layer has a diffusion coefficient for the target material of 1 x ^10-14 cm2 ^/ sec or less. 19. The target of claim 18, wherein the downstream layer has a diffusion coefficient for the target material of less than or equal to 1 x ^10-15 cm2 ^/ sec. 20. The target of claim 18, wherein the target material is lithium and the downstream layer has a diffusion coefficient for lithium of 5×10 ⁻¹⁴ cm ² /sec or less. 19. The target of claim 18, wherein the target material is lithium and the downstream layer has a diffusion coefficient for lithium of 5 x ^10-15 cm2 ^/ sec or less. 24. A target according to any of claims 18-23, wherein the downstream layer comprises lithium fluoride. 24. The downstream layer comprises lithium fluoride, lithium sulfide, magnesium fluoride, carbon (C), diamond-like carbon, (hyper)nanocrystalline diamond, or a polymer. target. 24. A target according to any of claims 18-23, wherein the downstream layer comprises lithium and no lithium nitride, lithium oxide or lithium hydroxide. 24. A target according to any of claims 18-23, wherein the downstream layer comprises neither aluminum nor beryllium. 28. A target according to any of claims 18-27, wherein the upstream layer is configured to seal against diffusion of ambient substances into the passivated region. 28. A target according to any of claims 18-27, wherein the upstream layer is configured to seal against diffusion of substances from the atmosphere into the passivated region. 28. A target according to any of claims 18-27, wherein the upstream layer is configured to seal against diffusion of oxygen, nitrogen and water into the passivated region. 28. A target according to any of claims 18-27, wherein the upstream layer is configured to seal against diffusion of ambient substances through the upstream layer of the passivation region and into contact with the downstream layer. 32. Any of claims 18-31, wherein the upstream layer comprises aluminum, titanium, platinum, nickel, steel, silver, gold, stainless steel, aluminum silicon, molybdenum, tungsten, tungsten carbide, and/or tantalum. Targets listed. 33. The upstream layer has a gas permeability for oxygen, nitrogen and carbon dioxide of 100 or less, measured in (cubic centimeters x millimeters)/(square meters x days x atmospheric pressure). target. 33. Any of claims 18-32, wherein the upstream layer has a gas permeability for oxygen, nitrogen and carbon dioxide of 3.1 or less, measured in (cubic centimeters x millimeters)/(square meters x days x atmospheric pressure). Targets described in. 35. The target of any of claims 18-34, wherein the upstream layer has a water vapor transmission rate (WTVR) measured in (grams x millimeters)/(square meter x day) of 0.6 or less. 35. The target of any of claims 18-34, wherein the upstream layer has a water vapor transmission rate (WTVR) of 0.09 or less, measured in (grams x millimeters)/(square meters x days). 37. A target according to any of claims 18-36, wherein the upstream layer is in contact with the downstream layer. 37. A target according to any of claims 18-36, wherein the passivation region comprises an intermediate layer between the upstream layer and the downstream layer. 39. A target according to any of claims 18-38, wherein the passivated region has a thickness of 10 microns or less. 39. A target according to any of claims 18-38, wherein the passivated region has a thickness of 3 microns or less. 41. A target according to any of claims 18-40, configured for use in a boron neutron capture therapy (BNCT) procedure. 42. The target of claim 41, configured to generate neutrons when exposed to a proton beam having an energy of 1.88 to 3.0 megaelectronvolts (MeV). 42. A target according to any of claims 18-41, wherein at least a portion of the passivated region is configured to be removed during operation. 44. A target according to any of claims 18-43, wherein the target material comprises lithium. A method of producing a target for boron neutron capture therapy, the method comprising:
applying a neutron generating region to a substrate;
applying a passivation region over the neutron generating region;
The neutron generation region comprises a target material configured to generate neutrons, and the passivation region is configured to seal against diffusion of the target material into the passivation region. That's the way it is. 46. The method of claim 45, wherein a layer downstream of the passivation region is configured to seal against diffusion of the target material into the passivation region. 47. The method of claim 46, further comprising applying an upstream layer of the passivation region over the downstream layer. 48. The method of claim 47, wherein the upstream layer is in contact with the downstream layer and/or the downstream layer is in contact with the neutron generating region. 49. The method of claim 48, wherein the neutron generating region and passivation region are configured according to any of claims 18-44. 49. The method of claim 48, wherein the neutron generating region and passivation region are configured according to any of claims 1-17. A method of producing neutrons, the method comprising:
applying the particle beam to the target such that particles from the particle beam generate neutrons when they traverse the passivated region and impact a neutron generating region of the target, the passivated region is configured to seal against diffusion of material of the neutron generating region into the passivation region;
continuing application of the particle beam to the target such that at least a portion of the passivated region is removed. 52. The method of claim 51, wherein the target is configured according to claims 1-44. 51. The passivation region comprises an upstream layer and a downstream layer, both the upstream layer and the downstream layer being removed by continued application of the particle beam within the target area. The method described in. 54. A method according to any of claims 51-53, carried out as part of a boron neutron capture therapy (BNCT) procedure. A target device, the target device comprising:
a substrate comprising a depression;
a neutron generating region within the recess of the substrate;
a passivation region positioned over the neutron generation region;
The passivation region includes an upstream layer and a downstream layer,
The targeting device, wherein the downstream layer is located within the recess. 56. The targeting device of claim 55, wherein the upstream layer is located within the recess. 56. The targeting device of claim 55, wherein the substrate includes a sidewall adjacent the recess, and the downstream layer does not extend over an upstream surface of the sidewall. 58. The targeting device of claim 57, wherein the upstream layer does not extend over the upstream surface of the sidewall. 58. The targeting device of claim 57, wherein the upstream layer extends over the upstream surface of the sidewall. 56. A targeting device according to claim 55, configured according to any of claims 18-44. A target device, the target device comprising:
a substrate;
a neutron generating region positioned over the substrate, the neutron generating region comprising an upstream surface and a sidewall surface;
a passivation region positioned over an upstream surface and a sidewall surface of the neutron generating region. 62. The targeting device of claim 61, wherein the passivation region and substrate surround the neutron generating region. 62. A targeting device according to claim 61, configured according to any of claims 1-17. 62. A targeting device according to claim 61, configured according to any of claims 18-44. A device, the device comprising:
a substrate;
a first region positioned over the substrate and comprising lithium;
a passivation region positioned over the first region;
The device, wherein the passivation region is configured to seal against diffusion of lithium into the passivation region. 66. The device of claim 65, wherein the first material is lithium and the passivated region has a diffusion coefficient for lithium of 5 x ^10-14 cm2 ^/ sec or less. 66. The device of claim 65, wherein the first material is lithium and the passivated region has a diffusion coefficient for lithium of 5 x ^10-15 cm2 ^/ sec or less. 68. A device according to any of claims 65-67, wherein the passivation region comprises lithium fluoride. 68. Any of claims 65-67, wherein the passivation region comprises lithium fluoride, lithium sulfide, magnesium fluoride, carbon (C), diamond-like carbon, (hyper)nanocrystalline diamond, or a polymer. Devices listed. 70. The device of any of claims 65-69, wherein the passivated region comprises lithium and no lithium nitride, lithium oxide or lithium hydroxide. 71. The device of any of claims 65-70, wherein the passivated region has a thickness of 100 microns or less. 71. The device of any of claims 65-70, wherein the passivated region has a thickness of 50 microns or less. A device, the device comprising:
a substrate;
a first region positioned over the substrate and comprising lithium;
a passivation region positioned over the first region and comprising a downstream layer and an upstream layer;
The device, wherein the downstream layer is configured to seal against diffusion of lithium into the passivated region. 74. The device of claim 73, wherein the downstream layer has a diffusion coefficient for lithium of 5×10 ⁻¹⁴ cm ² /sec or less. 74. The device of claim 73, wherein the downstream layer has a diffusion coefficient for lithium of ^5x10-15 cm2 ^/ sec or less. 76. A device according to any of claims 73-75, wherein the downstream layer comprises lithium fluoride. 76. The downstream layer comprises lithium fluoride, lithium sulfide, magnesium fluoride, carbon (C), diamond-like carbon, (hyper)nanocrystalline diamond, or a polymer. device. 76. The device of any of claims 73-75, wherein the downstream layer comprises lithium and no lithium nitride, lithium oxide or lithium hydroxide. 76. A device according to any of claims 73-75, wherein the downstream layer comprises neither aluminum nor beryllium. 80. A device according to any of claims 73-79, wherein the upstream layer is configured to seal against diffusion of ambient substances into the passivated region. 80. A device according to any of claims 73-79, wherein the upstream layer is configured to seal against diffusion of substances from the atmosphere into the passivated region. 80. The device of any of claims 73-79, wherein the upstream layer is configured to seal against diffusion of oxygen, nitrogen, and water into the passivated region. 80. The device of any of claims 73-79, wherein the upstream layer is configured to seal against the diffusion of ambient substances through the upstream layer of the passivation region and into contact with the downstream layer. 84. The upstream layer has a gas permeability for oxygen, nitrogen and carbon dioxide of 100 or less, measured in (cubic centimeters x millimeters)/(square meters x days x atmospheric pressure). device. 84. Any of claims 73-83, wherein the upstream layer has a gas permeability for oxygen, nitrogen, and carbon dioxide of 3.1 or less, measured in (cubic centimeters x millimeters)/(square meters x days x atmospheric pressure). Devices listed in. 86. The device of any of claims 73-85, wherein the upstream layer has a water vapor transmission rate (WTVR) of 0.6 or less, measured in (grams x millimeters)/(square meters x days). 86. The device of any of claims 73-85, wherein the upstream layer has a water vapor transmission rate (WTVR) of 0.09 or less, measured in (grams x millimeters)/(square meters x days). 88. Any of claims 73-87, wherein the upstream layer comprises aluminum, titanium, platinum, nickel, steel, silver, gold, stainless steel, aluminum silicon, molybdenum, tungsten, tungsten carbide, and/or tantalum. Devices listed. 89. A device according to any of claims 73-88, wherein the upstream layer is in contact with the downstream layer. 89. The device of any of claims 73-88, wherein the passivation region comprises an intermediate layer between the upstream layer and the downstream layer. 91. The device of any of claims 73-90, wherein the passivated region has a thickness of 100 microns or less. 91. The device of any of claims 73-90, wherein the passivated region has a thickness of 50 microns or less. A neutron beam system, the neutron beam system comprising:
accelerator and
a beam line extending from the accelerator to a neutron generation target configured according to any of claims 1-44.

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